This invention relates to a method for supplying a thread to a sewing machine and a hanger used therein.
Usually, in a sewing machine for industrial use, the thread is drawn out axially from a reel placed on a thread stand and fed to the sewing machine. If the thread is drawn out upwards, the reel need not be rotated. In industrial use, since the reel itself is large, in order to take out the thread by rotating the reel, a substantial force is required and it is almost impossible to accomplish this in the conventional sewing machine.
In order to draw out the thread upwardly, the direction from the reel to the sewing machine is changed by hooking the thread to a hanger such as a hook provided right above the installed reel.
For example, as shown in FIG. 7, the reel 10 is set on the thread stand 13 placed on a table 12 onto which the sewing machine 11 is installed. On a bottom plate 14 of the thread stand 13, a supporting rod 15 is erected to support the reel 10 by inserting the rod therethrough. Above the bottom plate 14, a horizontal arm 17, supported by an elongated rod 16, is provided and formed with hooks 18 on opposite ends thereof. A thread 19 from the reel 10, set on the supporting rod 15, is drawn out upwards from the reel 10 and supplied to the sewing machine 11 through the hook 18 of the horizontal arm 17.
However, a serious problem was encountered in the method of drawing out the thread axially from the reel to supply to the sewing machine. That is, when supplying the thread 19 from the reel 10 to the sewing machine 11, a twist loop 20 is not produced since a tension force is exerted on the thread during the operation of the sewing machine. However, if the sewing machine 11 is stopped when, for example, replacing the material being sewn, the thread 19 is loosened (indicated by the one-dot chain line in FIG. 7) and tends to produce the twist loop 20.
To "twist", as stated herein, is to fix one end of the thread and rotate the other end about the longitudinal thread axis, or to rotate both ends in opposite directions (refer to FIG. 8a). This twist happens in the same way when the thread is drawn out axially from the reel (refer to FIG. 8b). "Twist" also represents a twisted state of the thread.
To "loop-twist" is to produce a loop on the thread while twisting (refer to FIG. 8c). The loop produced by loop-twisting is called a twist-loop.
To "vertical-twist" is to rotate the thread at right angles to the lengthwise thread direction. Therefore, it is entirely different from the twisting of FIGS. 8a, b. The loop produced by the vertical-twist is called a vertical twist-loop (refer to FIG. 8d).
When a twist loop 20 is produced, it is sent to the sewing machine 11 through the prior art hook 18, so that there is a problem in that the hook is not caught by the adjuster of a thread tension adjusting device (not shown) of the sewing machine 11, or the loop causes a large resistance (refer to one-dot chain line in FIG. 7), consequently causing the sewing operation to stagnate seriously by breaking the thread, or causing an uneven seam due to unbalanced tension between the upper and lower thread; or breaking of needles, and so on.
Therefore, in the industry, there is a need for a method in which the twist 20 is not produced or, if produced, it is not brought to the sewing machine.